万家寨水库水环境特性分析

Analysis of Water Environment Characteristics of Wanjiazhai Reservoir

作为山西省的重要水源地,万家寨水库水环境质量对于山西省的供水安全具有重要意义。通过建立非结构单元的水环境数学模型,对现状情境下万家寨水库库区进行水动力过程模拟,分析最不利水文条件下区域内水环境特性。结果表明,水动力场显示,上游流量的大小对库区水体自净能力影响明显,研究区域水力停留时间最短出现在丰水年夏季,最长出现在枯水年冬季;在固定源连续排放下,枯水期、平水期、丰水期3种水文条件下,COD最大允许排放浓度分别为426、310 mg/L与252 mg/L;在枯水期、平水期、丰水期内,下游3个控制断面COD浓度均可达到二类水质标准时,污染物COD的水环境容量分别为14 060、15 959 t/d和18 137 t/d。

As an important water source in Shanxi Province,the water environment quality of Wanjiazhai Reservoir is of great significance to the water supply security of Shanxi Province.Based on unstructured grid,a mathematical model of water environment is established to simulate the hydrodynamic process in the reservoir area of Wanjiazhai Reservoir under current situation.The characteristics of water environment in the region are analyzed under the most unfavorable hydrological conditions.The results show that,(a)according to the hydrodynamic field analysis,the upstream flow rate has a significant influence on the self-purification capacity of water in reservoir area,and the shortest hydraulic retention time in the study area occurs in the summer of the high-flow year while the longest occurs in the winter of the low-flow year;(b)under the condition of continuous emission of sources,the highest permissive discharged concentration of COD are 426 mg/L,310 mg/L and 252 mg/L in low-flow period,moderate-flow period and high-flow period respectively;and(c)the water environment capacity of COD are 14060 t/d,15959 t/d and 18137 t/d in low-flow period,moderate-flow period and high-flow period respectively on the promise that the COD concentrations of three downstream control sections meet the second-class water quality standard.